Why Does Kerala's Kozhikode District See Repeated Nipah Infections? Experts Explain Why

The Nipah virus, a zoonotic virus responsible for 17 deaths during its first outbreak in Kerala in 2018, has reappeared in the state for the fourth time in five years.

Currently, six cases have been identified in 2023, all in Kerala's Kozhikode district.

Dr. A S Anoop Kumar, an infectious disease and tropical fever expert and the Director of Critical Care at Aster MIMS Hospital's North Kerala Cluster, has been instrumental in detecting the virus on multiple occasions, leading to timely containment of the outbreaks.

Dr. Anoop emphasizes the need for further research on Nipah and shares the meticulous investigation conducted when a family of four was admitted to MIMS Kozhikode. Their efforts included isolating patients, implementing Nipah protocols, and ensuring proper containment measures.

Reason for Repeated Nipah Infections in Kerala

Dr. Anoop explains some possible explanations for the recurrence of Nipah infections in Kerala.

During the 2018 outbreak, it was established that bats in the Kozhikode area carry the Nipah virus, and the same strain of the virus was found in all cases, confirming bats as the source of infection.

However, data also indicate the virus presence in bats from other states. The reason other states do not report Nipah cases might be due to a lack of suspicion and insufficient testing of samples.

Fruit Bats Acting as a Reservoir

Dr. Anoop points out that all fruit bats in India, except in certain parts of Kashmir, are reservoirs of the Nipah virus.

However, there is no scientific evidence regarding the virus's density specifically in fruit bats in Kerala compared to other regions.

Why Kerala Reports More Suspected Cases

Kerala's healthcare system, informed and proactive citizens, and well-established healthcare infrastructure contribute to the higher reporting of suspected cases.

Comparison with West Bengal

In contrast, West Bengal has not reported Nipah cases since the outbreaks in 2001 and 2007. Dr. Anoop suggests that this may be due to differences in healthcare practices and a cautious approach to screening only when there is a high suspicion of infection.

Additionally, the source of infection may not be within that specific area, providing some protection to the population.

Symptoms in 2018 vs. 2023

Dr. Anoop notes a significant change in Nipah symptoms between the 2018 and 2023 cases.

In 2018, patients primarily exhibited encephalitis symptoms, while the current cases predominantly display respiratory symptoms and severe pneumonia, with encephalitis symptoms less prominent.

This shift suggests a genetic variation or mutation in the virus, which needs further investigation by the National Institute of Virology, Pune.

Timeline of Detection in 2023

Dr. Anoop outlines the timeline of events leading to the virus's detection in 2023.

A family of four was admitted to MIMS Kozhikode, and suspicion arose when one member died on August 30. The first patient's death was considered the index case.

A new patient with viral pneumonia arrived on September 11, raising suspicion due to the overlapping time frame with the index case. The investigation led to the conclusion that the August 30 death was indeed the index case, prompting containment measures.

Evolution of Kerala's Response

Dr. Anoop highlights the evolution of Kerala's response to Nipah since the initial outbreak.

The experience gained from managing Covid-19 has made the healthcare system more efficient in handling outbreaks like Nipah. Health workers are now experienced in dealing with viral pathogens and equipped with necessary precautions.

Transmission in Healthcare Institutions

Similar to past outbreaks, Nipah transmission in the current situation has primarily occurred within healthcare institutions. Improved infection control measures have been implemented since 2018, reducing the risk of major outbreaks.

However, there may have been a breach in infection control policies, leading to the infection of a health worker and subsequent transmission within the healthcare institution.

Research on Nipah

Dr. Anoop emphasizes the need for further research on Nipah. Studies should focus on survivors to understand antibody development and immunity.

Monoclonal antibodies' effectiveness in treating Nipah patients, especially in the early stages, requires investigation. Additionally, research should explore genetic factors that may protect individuals from the virus.

Preventing Future Outbreaks

To prevent future outbreaks, Dr. Anoop stresses the importance of disease surveillance, compulsory testing for Nipah in cases of fever deaths, undiagnosed encephalitis, and respiratory diseases that test negative for other viruses.

Proper screening and diagnosis of individuals with encephalitis and thorough investigations into undiagnosed fever deaths are crucial. Ensuring availability sufficient testing facilities in Kerala is also necessary.